Oñate, Don Juan de, the founder and first governor of New Mexico, was the son of a conquistador, rich and popular, and prior to the establishment of New Mexico was a citizen of Zacatecas. Thwaites, in his "Early Western Travels," says that either his wife or his mother was a granddaughter of Hernando de Cortez. In 1601, guided by a survivor of the ill-fated expedition of Bonilla (q. v.) of six years before, Oñate left Santa Fe with a force of 80 men to go in search of Quivira. Two priests, the padres Vergara and Velasco, accompanied the expedition. After marching across the plains in a northeasterly direction for 200 leagues, to an estimated latitude of 39° or 40° he fell in with a tribe of Indians called the Escanjaques, with whom he formed an alliance and continued his march toward the province of Quivira. The alliance evidently did not last long, as Bancroft says: "The Spaniards had a battle with the Escanjaques and killed 1,000 of them on the Matanza plain, the scene of Humana's defeat. The battle was caused by Padre Velasco's efforts to prevent the Escanjaques from destroying the property of the Quiviras, who had fled from their towns at the approach of the Spaniards and their allies."

The Spanish loss in the engagement was slight, but the trouble with the Indian allies gave an unfortunate turn to the expedition. Owing to a lack of definite information, it is impossible to determine just how far Oñate went into the Indian country. The imperfect reports say that large villages were seen, and that advance parties claimed to have seen utensils of gold and silver, which metals were reported to be plentiful in the country of the Aijados not far away. If Oñate reached a point as far north as 39° he was no doubt somewhere in the Smoky 1—Ell valley in central Kansas. Bancroft thinks that "It is not quite clear that Quivira was actually visited, but ambassadors from that people—also called Tindanes—were met, who wanted to join the Spaniards in a raid on the gold country. Oñate, however, deemed it unwise to go on with so small a force, or perhaps was turned back by the clamors of his men."

Oñate returned to New Mexico in the fall, probably in October, and he was still governor of that province as late as 1608. His death is supposed to have occurred about 1620. His expedition was only one of many futile attempts of the Spaniards of the southwest to discover rich mines and establish friendly relations with the natives.